U.S. patent application number 13/369771 was filed with the patent office on 2013-01-31 for hose for refrigerant transport use.
The applicant listed for this patent is Susumu Hatanaka, Yuusuke Matsuya, Hideyuki Oishi, Koji Sato, Kazuto Yamakawa. Invention is credited to Susumu Hatanaka, Yuusuke Matsuya, Hideyuki Oishi, Koji Sato, Kazuto Yamakawa.
Application Number | 20130025733 13/369771 |
Document ID | / |
Family ID | 43586087 |
Filed Date | 2013-01-31 |
United States Patent
Application |
20130025733 |
Kind Code |
A1 |
Yamakawa; Kazuto ; et
al. |
January 31, 2013 |
HOSE FOR REFRIGERANT TRANSPORT USE
Abstract
A hose for refrigerant transport use comprising an inner layer
with superior deterioration resistance performance. The innermost
layer comprised in the hose for refrigerant transport use of the
present invention is formed using a polyamide resin composition
comprising a polyamide and, per 100 parts by mass thereof, from 0.5
to 20 parts by mass of an acid acceptor.
Inventors: |
Yamakawa; Kazuto;
(Hiratsuka, JP) ; Matsuya; Yuusuke; (Hiratsuka,
JP) ; Sato; Koji; (Hiratsuka, JP) ; Hatanaka;
Susumu; (Hiratsuka, JP) ; Oishi; Hideyuki;
(Hiratsuka, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Yamakawa; Kazuto
Matsuya; Yuusuke
Sato; Koji
Hatanaka; Susumu
Oishi; Hideyuki |
Hiratsuka
Hiratsuka
Hiratsuka
Hiratsuka
Hiratsuka |
|
JP
JP
JP
JP
JP |
|
|
Family ID: |
43586087 |
Appl. No.: |
13/369771 |
Filed: |
February 9, 2012 |
Current U.S.
Class: |
138/137 |
Current CPC
Class: |
Y10T 428/1393 20150115;
B32B 25/10 20130101; C08K 3/22 20130101; C08L 77/02 20130101; B32B
25/08 20130101; B32B 27/32 20130101; B32B 1/08 20130101; F16L 11/08
20130101; B32B 2250/04 20130101; B32B 2307/7265 20130101; C08L
77/06 20130101; B32B 27/34 20130101; B32B 27/18 20130101; C08K 3/26
20130101; C08L 77/02 20130101; C08L 51/06 20130101; C08L 51/06
20130101; C08L 51/06 20130101; C08L 51/06 20130101; C08K 3/26
20130101; C08K 3/22 20130101; C08L 51/06 20130101; B32B 2597/00
20130101; C08L 77/06 20130101; B32B 2264/102 20130101; C08K 3/22
20130101; C08K 3/26 20130101; C08L 77/02 20130101; B60H 1/00571
20130101; C08L 77/06 20130101; F16L 11/04 20130101; B32B 2270/00
20130101; Y10T 428/139 20150115 |
Class at
Publication: |
138/137 |
International
Class: |
F16L 11/04 20060101
F16L011/04 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 12, 2009 |
JP |
2009-187305 |
Feb 2, 2010 |
JP |
2010-020912 |
Claims
1. A hose for refrigerant transport use comprising: an innermost
layer formed using a polyamide resin composition comprising a
polyamide and, per 100 parts by mass thereof, from 0.5 to 20 parts
by mass of an acid acceptor; wherein the hose for refrigerant
transport use is used for a refrigerant-containing composition
comprising a fluorine-based compound having a double bond as a
refrigerant.
2. The hose for refrigerant transport use according to claim 1,
wherein the acid acceptor is at least one selected from the group
consisting of a metal compound, an inorganic microporous crystal,
and a hydrotalcite.
3. The hose for refrigerant transport use according to claim 2,
wherein the metal compound is at least one selected from the group
consisting of: oxides, hydroxides, carbonates, carboxylates,
silicates, borates, and phosphites of the periodic table group 2
and group 12 metals; oxides, hydroxides, carboxylates, silicates,
sulfates, nitrates, and phosphates of the periodic table group 3
and group 13 metals; and oxides, basic carbonates, basic
carboxylates, basic phosphites, basic sulfites, and tribasic
sulfates of the periodic table group 4 and group 14 metals.
4. The hose for refrigerant transport use according to claim 2,
wherein the metal compound is at least one selected from the group
consisting of: magnesium oxide, calcium hydroxide, magnesium
hydroxide, aluminum hydroxide, barium hydroxide, sodium carbonate,
magnesium carbonate, barium carbonate, calcium oxide, calcium
carbonate, calcium silicate, calcium stearate, zinc stearate, zinc
oxide, calcium phthalate, calcium phosphite, tin oxide, litharge,
red lead, dibasic lead phthalate, dibasic lead carbonate, tin
stearate, basic lead phosphite, basic tin phosphite, basic lead
sulfite, and tribasic lead sulfate.
5. The hose for refrigerant transport use according to claim 1,
wherein the polyamide resin composition further comprises a
carboxyl group-containing modified polyolefin.
6. The hose for refrigerant transport use according to claim 1,
wherein the polyamide is at least one selected from the group
consisting of polyamide 6, polyamide 11, polyamide 12, polyamide
4-6, polyamide 6-6, polyamide 6-10, polyamide 6-12, and polyamide
MXD6.
7. The hose for refrigerant transport use according to claim 1,
wherein the fluorine-based compound is at least one fluoropropene
selected from the group consisting of 1,2,3,3,3-pentafluoropropene,
1,3,3,3-tetrafluoropropene, 2,3,3,3-tetrafluoropropene,
1,2,3,3-tetrafluoropropene, and 3,3,3-trifluoropropene.
8. The hose for refrigerant transport use according to claim 1,
wherein the polyamide resin composition further comprises an acid
sealing agent.
9. The hose for refrigerant transport use according to claim 8,
wherein the acid sealing agent is at least one selected from the
group consisting of a carbodiimide compound, an epoxy compound, an
amine compound, an isocyanate compound, and an alcohol.
10. The hose for refrigerant transport use according to claim 9,
wherein an epoxy equivalent weight of the epoxy compound is from
140 to 3,300 g/eq.
11. The hose for refrigerant transport use according to claim 8,
wherein an amount of the acid sealing agent is from 0.1 to 10 parts
by mass per 100 parts by mass of the polyamide.
12. The hose for refrigerant transport use according to claim 1
comprising a rubber layer on the innermost layer, a reinforcing
layer on the rubber layer, and an outer layer on the reinforcing
layer.
13. The hose for refrigerant transport use according to claim 1,
wherein a Young's modulus of a hardened product formed from the
polyamide resin composition, after a test in which the hardened
product is immersed in the refrigerant-containing composition
further comprising water, is 300 MPa or less.
14. The hose for refrigerant transport use according to claim 5,
wherein a weight ratio (mass ratio) of the polyamide to the
carboxyl group-containing modified polyolefin is from 90/10 to
50/50.
15. The hose for transporting refrigerant according to claim 1,
wherein the acid acceptor is a hydrotalcite.
16. The hose for refrigerant transport use according to claim 1,
wherein the acid acceptor is represented by the chemical formula:
Mg.sub.1-xAl.sub.xO.sub.3.83x (0.2.ltoreq.x<0.5).
Description
TECHNICAL FIELD
[0001] The present invention relates to a hose for refrigerant
transport use.
BACKGROUND ART
[0002] Currently, since HFC134a, which is used as a refrigerant in
car air conditioning systems, has a large global warming potential
(GWP), HFO1234yf, which has a small GWP, has emerged as a promising
new refrigerant candidate to replace HFC134a. For example, Japanese
Unexamined Patent Application Publication No. 2009-074017A proposes
a composition comprising a refrigerant such as HFO1234yf and a
lubricating oil.
[0003] Additionally, conventionally, laminated structures of a
rubber and a resin comprising an innermost layer formed from a
polyamide resin material in order to suppress the permeation of a
refrigerant have been commonly used for rubber hoses for use in car
air conditioning systems.
SUMMARY OF THE INVENTION
[0004] However, the inventors discovered that when a refrigerant
composition comprising a fluorine-based compound having double
bonds such as HFO-1234yf as a refrigerant and a lubricating oil was
applied to a conventional rubber hose for use in car air
conditioning systems, deterioration resistance performance
(durability) of the innermost layer of the hose with respect to the
new refrigerant is low.
[0005] Therefore, an object of the present invention is to provide
a hose for refrigerant transport use comprising an innermost layer
that displays superior deterioration resistance performance.
[0006] As a result of diligent research into a solution for the
problem describe above, the inventors discovered that an innermost
layer formed using a polyamide resin composition comprising a
polyamide and an acid acceptor has superior deterioration
resistance performance, and thus arrived at the present
invention.
[0007] Specifically, the present invention provides the following 1
to 12.
[0008] 1. A hose for refrigerant transport use comprising an
innermost layer formed using a polyamide resin composition
comprising a polyamide and, per 100 parts by mass thereof, from 0.5
to 20 parts by mass of an acid acceptor.
[0009] 2. The hose for refrigerant transport use described in 1,
wherein the acid acceptor is at least one selected from the group
consisting of hydrotalcite, magnesium oxide, and calcium
hydroxide.
[0010] 3. The hose for refrigerant transport use described in 1 or
2, wherein the polyamide resin composition further comprises a
carboxyl group-containing modified polyolefin.
[0011] 4. The hose for refrigerant transport use described in any
one of 1 to 3, wherein the polyamide is at least one selected from
the group consisting of polyamide 6, polyamide 11, polyamide 12,
polyamide 4-6, polyamide 6-6, polyamide 6-10, polyamide 6-12, and
polyamide MXD6.
[0012] 5. The hose for refrigerant transport use described in 3 or
4, wherein a weight ratio (mass ratio) of the polyamide to the
carboxyl group-containing modified polyolefin is from 90/10 to
50/50.
[0013] 6. The hose for refrigerant transport use described in any
one of 1 to 5 used for a refrigerant-containing composition
comprising a fluorine-based compound having double bonds as a
refrigerant.
[0014] 7. The hose for refrigerant transport use described in 6,
wherein the fluorine-based compound is at least one fluoropropene
selected from the group consisting of 1,2,3,3,3-pentafluoropropene,
1,3,3,3-tetrafluoropropene, 2,3,3,3-tetrafluoropropene,
1,2,3,3-tetrafluoropropene, and 3,3,3-trifluoropropene.
[0015] 8. The hose for refrigerant transport use described in any
one of 1 to 7, wherein the polyamide resin composition further
comprises an acid sealing agent.
[0016] 9. The hose for refrigerant transport use described in 8,
wherein the acid sealing agent is at least one selected from the
group consisting of a carbodiimide compound, an epoxy compound, an
amine compound, an isocyanate compound, and an alcohol.
[0017] 10. The hose for refrigerant transport use described in 9,
wherein an epoxy equivalent weight of the epoxy compound is from
140 to 3,300 g/eq.
[0018] 11. The hose for refrigerant transport use described in any
one of 8 to 10, wherein an amount of the acid sealing agent is from
0.1 to 10 parts by mass per 100 parts by mass of the polyamide.
[0019] 12. The hose for refrigerant transport use described in any
one of 1 to 11 comprising a rubber layer on the innermost layer, a
reinforcing layer on the rubber layer, and an outer layer on the
reinforcing layer.
EFFECT OF THE INVENTION
[0020] The hose for refrigerant transport use of the present
invention comprises an innermost layer that displays superior
deterioration resistance performance.
BRIEF DESCRIPTION OF THE DRAWING
[0021] FIG. 1 is a perspective view schematically illustrating a
cutaway of each layer of a hose that is an example of the hose for
refrigerant transport use of the present invention.
[0022] FIGS. 2a-2b include a Table of comparative and working
examples in accordance with examples of the present technology.
DETAILED DESCRIPTION
[0023] The present invention is described in detail below.
[0024] A hose for refrigerant transport use of the present
invention comprises an innermost layer formed using a polyamide
resin composition comprising a polyamide and, per 100 parts by mass
thereof, from 0.5 to 20 parts by mass of an acid acceptor.
[0025] The hose for refrigerant transport use of the present
invention comprises an innermost layer that displays superior
deterioration resistance performance.
[0026] In the present invention, "deterioration resistance
performance of the innermost layer" refers to the suppression of
chemically induced deterioration of the resin due to attacks by new
refrigerants, chemicals, or the like.
[0027] Conventionally, a refrigerant-containing composition
comprising a refrigerant and a lubricating oil had been applied to
a hose for refrigerant transport use, and this
refrigerant-containing composition is passed through the hose for
refrigerant transport use. When using the hose for refrigerant
transport use for an extended period of time, in some cases, while
a small amount, water permeates through the hose for refrigerant
transport use and contaminates the refrigerant-containing
composition. Such contamination by water invites deterioration of
the refrigerant-containing composition when used under
high-temperature conditions. Acidic components (e.g. components
thought to be hydrogen fluoride) are produced from the
refrigerant-containing composition, and it is thought that these
acidic components act as catalysts that hydrolyze the polyamide
used in the innermost layer of the hose for refrigerant transport
use. This hydrolysis of the polyamide leads to a decline in the
deterioration resistance performance of the innermost layer.
[0028] In the present invention, an acid acceptor can trap the
acidic components. It is possible for the acid acceptor to trap the
acidic components by reacting with the acidic components.
[0029] The hydrolysis of the polyamide can be suppressed by the
trapping of the acidic components by the acid acceptor. The present
inventors have deduced that superior deterioration resistance
performance of the innermost layer will be obtained due to the
suppressing the hydrolysis of the polyamide in such a manner.
[0030] Additionally, the acid acceptor can trap carboxylic acids
that are present in the innermost layer and/or acids produced via
the hydrolysis of lubricants such as ester-based oil that are
included in the refrigerant-containing composition. It is possible
for the acid acceptor to trap the acid by reacting with the
acid.
[0031] The acid is not particularly limited as long as it is a
compound having at least one acidic group (e.g. carboxy group).
Examples thereof include acids such as carboxylic acid, phosphoric
acid, and sulfonic acid; and partial esters of acids. Examples of
the partial esters include partial esters that have at least one
acidic group and at least one ester.
[0032] Specific examples of the acid include carboxylic acid
present in the innermost layer and acids that are produced via the
hydrolysis of lubricants such as ester-based oil included in the
refrigerant-containing composition applied to the hose for
refrigerant transport use. Examples of the carboxylic acid present
in the innermost layer include carboxylic acids that attach to an
end of a polyamide, and carboxylic acids that are produced via a
polyamide hydrolyzing as a result of being affected by the
deterioration or the like of the refrigerant-containing
composition.
[0033] The acid acceptor can suppress the hydrolysis of the
polyamide by reacting with the carboxylic acid that attaches to an
end of a polyamide, the acid that is produced via a polyamide
hydrolyzing as a result of being affected by the deterioration or
the like of the refrigerant-containing composition, or an acid
produced from the refrigerant-containing composition. The present
inventors have deduced that an innermost layer having superior
deterioration resistance performance will be obtained by
suppressing the hydrolysis of the polyamide in such a manner.
[0034] Note that the mechanism described above is a deduction of
the present inventors, and, even in cases involving different
mechanisms, such mechanisms are within the scope of the present
invention.
[0035] An example of a preferred embodiment of the hose for
refrigerant transport use of the present invention is described
below while referencing the attached drawing. However, the present
invention is not limited to the attached drawing.
[0036] FIG. 1 is a perspective view schematically illustrating a
cutaway of each layer of a hose that is an example of the hose for
refrigerant transport use of the present invention.
[0037] A hose for refrigerant transport use 1 illustrated in FIG. 1
comprises an inner tube 6, a reinforcing layer 7, and an outer
layer 9. The inner tube 6 has an innermost layer 3 and a rubber
layer 5. The rubber layer 5 is on the innermost layer 3 (inner
surface resin layer), the reinforcing layer 7 is on the rubber
layer 5, and the outer layer 9 is on the reinforcing layer 7.
[0038] The hose for refrigerant transport use comprising an inner
tube, a reinforcing layer, and an outer layer, with the inner tube
comprising an innermost layer (inner surface resin layer) and a
rubber layer is an example of a preferred form of the hose for
refrigerant transport use of the present invention.
[0039] From the perspectives of obtaining an innermost layer that
is superior with regards to deterioration resistance performance
and achieves superior flexibility (flexibility of the innermost
layer and the entire hose), a thickness of the innermost layer is
preferably from 0.05 to 0.3 mm.
[0040] From the perspectives of achieving superior fatigue
resistance performance and superior flexibility (flexibility of the
rubber layer and the entire hose), a thickness of the rubber layer
is preferably from 1.0 to 2.0 mm.
[0041] From the perspectives of achieving superior fatigue
resistance performance and superior flexibility (flexibility of the
reinforcing layer and the entire hose), a thickness of the
reinforcing layer is preferably from 0.5 to 1.5 mm.
[0042] From the perspectives of achieving superior fatigue
resistance performance and superior flexibility (flexibility of the
outer layer and the entire hose), a thickness of the outer layer is
preferably from 0.5 to 1.5 mm.
[0043] A description of the innermost layer is given below.
[0044] The innermost layer comprised in the hose for refrigerant
transport use of the present invention is formed using a polyamide
resin composition comprising a polyamide and, per 100 parts by mass
thereof, from 0.5 to 20 parts by mass of an acid acceptor.
[0045] The acid acceptor is not particularly limited. Examples of
the acid acceptor include metal compounds, inorganic microporous
crystals, and hydrotalcites.
[0046] Examples of the metal compounds include oxides, hydroxides,
carbonates, carboxylates, silicates, borates, and phosphites of
periodic table group II (group 2 and group 12 elements) metals;
oxides, hydroxides, carboxylates, silicates, sulfates, nitrates,
and phosphates of periodic table group III (group 3 and group 13
elements) metals; and oxides, basic carbonates, basic carboxylates,
basic phosphites, basic sulfites, tribasic sulfates of periodic
table group IV (group 4 and group 14 elements) metals, and the
like.
[0047] Specific examples of the metal compounds include magnesium
oxide (MgO, magnesia), calcium hydroxide, magnesium hydroxide,
aluminum hydroxide, barium hydroxide, sodium carbonate, magnesium
carbonate, barium carbonate, calcium oxide, calcium carbonate,
calcium silicate, calcium stearate, zinc stearate, zinc oxide,
calcium phthalate, calcium phosphite, tin oxide, litharge, red
lead, white lead, dibasic lead phthalate, dibasic lead carbonate,
tin stearate, basic lead phosphite, basic tin phosphite, basic lead
sulfite, tribasic lead sulfate, and the like.
[0048] From the perspectives of obtaining an innermost layer that
is superior with regards to deterioration resistance performance
(specifically, resistance to a decline in the mechanical properties
of the innermost layer such as breaking elongation over an extended
period of time) and achieving superior environmental safety, the
acid acceptor is preferably at least one selected from the group
consisting of hydrotalcite, magnesium oxide, and calcium
hydroxide.
[0049] Additionally, from the perspectives of not easily releasing
a trapped halogen, obtaining an innermost layer that is superior
with regards to deterioration resistance performance (specifically,
resistance to a decline in the mechanical properties of the
innermost layer such as breaking elongation over an extended period
of time), achieving superior environmental safety, and obtaining a
polyamide resin composition that is not prone to gelling and easily
forms a film, the acid acceptor is preferably a hydrotalcite.
[0050] The hydrotalcite used as the acid acceptor is not
particularly limited. The hydrotalcite may be a natural or a
synthetic hydrotalcite. Specific examples include the
following:
[0051] Mg.sub.3ZnAl.sub.2(OH).sub.12CO.sub.3.wH.sub.2O (wherein, w
is a positive real number);
[0052] Mg.sub.xAl.sub.y(OH).sub.2x+3y-2CO.sub.3.wH.sub.2O (wherein,
x is from 1 to 10, y is from 1 to 10, and w is a positive real
number);
[0053] Mg.sub.xAl.sub.y(OH).sub.2x+3y-2CO.sub.3 (wherein, x is from
1 to 10 and y is from 1 to 10. Specific examples include
Mg.sub.4.3Al.sub.2(OH).sub.12.6CO.sub.3 (Trade name: DHT-4A-2,
manufactured by Kyowa Chemical Industry Co., Ltd.); and
[0054] Mg.sub.1-xAl.sub.xO.sub.3.83x (0.2.ltoreq.x<0.5 Specific
examples include Mg.sub.0.7Al.sub.0.3O.sub.1.15 (Trade name:
KW-2200, manufactured by Kyowa Chemical Industry Co., Ltd.).
[0055] Chemical equations according to which the hydrotalcite
reacts with the acid and traps the halogen (e.g. halogen-containing
acid; here, hydrofluoric acid is given as an example) are shown
below.
Mg.sub.4.3Al.sub.2(OH).sub.12.6CO.sub.3+2HF.fwdarw.Mg.sub.4.3Al.sub.2(OH-
).sub.12.6F.sub.2+H.sub.2O+CO.sub.2 Chemical Equation 1
Mg.sub.0.7Al.sub.0.3O.sub.1.15+0.3HF+0.85H.sub.2O.fwdarw.Mg.sub.0.7Al.su-
b.0.3(OH).sub.2F.sub.0.3 Chemical Equation 2
[0056] The halogen trapped by the hydrotalcite and included in a
reaction product is not released from the reaction product as long
as the reaction product does not decompose as a result of heating
at 450.degree. C. or greater.
[0057] A maximum usage temperature of hoses for use in car air
conditioning systems is approximately 150.degree. C. Therefore, in
cases where the hose for refrigerant transport use is used in car
air conditioning system applications, there is a benefit in that
trapped halogen will not be released. From this perspective as
well, a hydrotalcite is preferably used as the acid acceptor.
[0058] Among hydrotalcites, from the perspectives of obtaining an
innermost layer that is superior with regards to deterioration
resistance performance, achieving higher halogen trapping capacity,
and not producing water or carbon dioxide after trapping the
halogen, hydrotalcites that have low OH contents or
Mg.sub.1-xAl.sub.xO.sub.3.83x are preferable and
Mg.sub.0.7Al.sub.0.3O.sub.1.15 is more preferable. The hydrotalcite
having a low OH content in the chemical structure can be produced
by baking a hydrotalcite obtained via synthesis at an elevated
temperature.
[0059] A commercially available product can be used as the
hydrotalcite. Examples of commercially available hydrotalcites
include the DHT series (DHT-4A-2, DHT-4C) manufactured by Kyowa
Chemical Industry Co., Ltd., the KW series (grade obtained by
baking the DHT series at a higher temperatures. It tends to have a
higher halogen trapping capacity than the DHT series; KW-2000,
KW-2100, and KW-2200) also manufactured by Kyowa Chemical Industry
Co., Ltd., and the STABIACE HT series manufactured by Sakai
Chemical Industry Co., Ltd.
[0060] The acid acceptor may be a natural or synthetic acid
acceptor. When the acid acceptor is a synthetic acid acceptor, a
manufacturing method thereof may be a conventional method.
[0061] From the perspective of achieving increased halogen trapping
capacity, the acid acceptor may be one which has not been surface
treated by a fatty acid (including higher fatty acids), a fatty
acid ester, or the like.
[0062] A single acid acceptor can be used or a combination of two
or more acid acceptors can be used.
[0063] In the present invention, an amount of the acid acceptor is
from 0.5 to 20 parts by mass per 100 parts by mass of the
polyamide. When within such a range, superior deterioration
resistance performance of the innermost layer, superior flexibility
(low flexural rigidity of the hose itself and good manageability in
an engine room), and superior vibration resistance (vibration from
a compressor used to compress the refrigerant does not easily
transfer to a vehicle body side and effects of vibration and noise
experienced in the vehicle are minimal) are obtained.
[0064] Additionally, from the perspectives of obtaining an
innermost layer having superior deterioration resistance
performance and achieving superior flexibility (flexibility of the
innermost layer and the entire hose), the amount of the acid
acceptor is preferably from 2 to 15 parts by mass and more
preferably from 3 to 15 parts by mass per 100 parts by mass of the
polyamide.
[0065] A description of the polyamide is given below.
[0066] In the present invention, the polyamide comprised in the
polyamide resin composition is not particularly limited.
[0067] From the perspective of achieving superior refrigerant
permeation resistance, the polyamide is preferably at least one
selected from the group consisting of polyamide 6, polyamide 11,
polyamide 12, polyamide 4-6, polyamide 6-6, polyamide 6-10,
polyamide 6-12, and polyamide MXD6.
[0068] Even if the polyamide resin composition comprises a
polyamide that is prone to hydrolysis (e.g., polyamide 6), the
innermost layer of the hose for refrigerant transport use of the
present invention can display superior deterioration resistance
performance.
[0069] A single polyamide can be used or a combination of two or
more polyamides can be used.
[0070] In the present invention, the polyamide resin composition
can further comprise a carboxyl group-containing modified
polyolefin. From the perspectives of obtaining an innermost layer
that is superior with regards to deterioration resistance
performance, and achieving superior flexibility (flexibility of the
innermost layer and the entire hose), superior vibration
resistance, and superior affinity with the polyamide, the polyamide
resin composition preferably further comprises the carboxyl
group-containing modified polyolefin.
[0071] The carboxyl group-containing modified polyolefin is not
particularly limited as long as it is a polyolefin that has a
carboxyl group. Additionally, a preferable form of the polyamide
comprised in the polyamide resin composition is a modified
polyamide obtained by blending the polyamide and the carboxyl
group-containing modified polyolefin.
[0072] Note that it is sufficient that the innermost layer (gas
barrier layer) be formed from the polyamide resin composition (e.g.
a preferable form comprises one of the modified polyamides
described above), and may comprise other components (e.g. additives
and the like) as long as the object of the present invention can be
achieved. Cases where such other components are comprised are
within the scope of the present invention.
[0073] Examples of a preferable carboxyl group-containing modified
polyolefin comprises a modified polyolefin wherein from about 0.1
to 10 mol % of a functional group is introduced via graft
polymerization of an acid anhydride such as maleic anhydride to a
polyolefin which is a homopolymerized or copolymerized olefin such
as ethylene, propylene, butadiene, and the like or diene monomer
such as butadiene, and the like.
[0074] From the perspective of achieving superior flexibility
(flexibility of the innermost layer and the entire hose), a weight
ratio (polyamide/carboxyl group-containing modified polyolefin,
mass ratio) of the polyamide to the carboxyl group-containing
modified polyolefin is preferably from 90/10 to 50/50 and more
preferably from 85/15 to 65/35. If a proportion of the carboxyl
group-containing modified polyolefin is 50 mass % or less,
refrigerant permeation resistance will be superior. If the
proportion of the carboxyl group-containing modified polyolefin is
10 mass % or greater, flexibility (flexibility of the innermost
layer and the entire hose) will be superior.
[0075] Examples of the modified polyamide include Zytel ST series
products such as Zytel ST801, Zytel ST811, and Zytel ST811HS
(manufactured by DuPont), thought to be produced by alloying
polyamide 6 and a maleic anhydride modified polyolefin (blended
product).
[0076] The innermost layer (gas barrier layer) can be formed by
extrusion molding the modified polyamide into, for example, a tube
shape.
[0077] From the perspectives of obtaining an innermost layer that
is superior with regards to deterioration resistance performance
(specifically, resistance to a decline in the mechanical properties
of the innermost layer such as breaking elongation over an extended
period of time), achieving superior flexibility (flexibility of the
innermost layer and the entire hose), achieving superior
environmental safety, not easily releasing a trapped halogen, and
obtaining a polyamide resin composition that is not prone to
gelling and easily forms a film, the polyamide resin composition
preferably comprises the polyamide, the carboxyl group-containing
modified polyolefin, and the hydrotalcite.
[0078] In the present invention, the polyamide resin composition
can further comprises an acid sealing agent.
[0079] If the polyamide resin composition further comprises the
acid sealing agent, an innermost layer that is superior with
regards to deterioration resistance performance can be
obtained.
[0080] In the present invention, the acid sealing agent can seal or
trap (hereinafter referred to as "seal, etc.") acid. The acid
sealing agent seals, etc. acid by reacting with an acid.
[0081] The acid is not particularly limited as long as it is a
compound having at least one acidic group (e.g. carboxy group).
Examples thereof include acids such as carboxylic acid, phosphoric
acid, and sulfonic acid; and, when the acid as two or more acidic
groups, partial esters thereof. The partial ester has at least one
acidic group and at least one ester.
[0082] Specific examples of the acid include carboxylic acids such
as the carboxylic acid present in the innermost layer and the
carboxylic acid that is produced via hydrolysis of lubricants such
as the ester-based oil present in the refrigerant-containing
composition applied to the hose for refrigerant transport use;
phosphoric acid that is produced via the hydrolyzing of phosphate
ester-based additives included in the lubricant; and sulfonic
acid.
[0083] Examples of the carboxylic acid present in the innermost
layer include carboxylic acids that attach to an end of a
polyamide, and carboxylic acids that are produced via a polyamide
hydrolyzing as a result of being affected by the deterioration or
the like of the refrigerant-containing composition.
[0084] Examples of the phosphoric acid include phosphate partial
esters with high acidity that are produced via the hydrolyzing of
additives such as the triaryl phosphate ester included in the
lubricant such as the ester-based oil contained in the
refrigerant-containing composition.
[0085] The acid sealing agent can suppress the hydrolysis of the
polyamide by sealing the carboxylic acid that attaches to the end
of the polyamide or by sealing or trapping the carboxylic acid that
is produced via the polyamide hydrolyzing as a result of being
affected by the deterioration or the like of the
refrigerant-containing composition or the acid produced from the
refrigerant-containing composition. The present inventors have
deduced that the deterioration resistance performance of the
innermost layer will be superior due to the suppressing the
hydrolysis of the polyamide in such a manner.
[0086] In addition to sealing the acid, the acid sealing agent can
also trap acidic components produced from the
refrigerant-containing composition.
[0087] Note that the mechanism described above is a deduction of
the present inventors, and, even should the mechanism differ, such
a mechanism is within the scope of the present invention.
[0088] The acid sealing agent is not particularly limited as long
as it is a compound that can seal, etc. acid (including partial
esters). Moreover, the acid sealing agent can, for example, trap
acid produced from the refrigerant-containing composition.
[0089] Examples of the functional group capable of reacting with
the acid included in the acid sealing agent include carbodiimide
groups, epoxy groups, amino groups, isocyanate groups, and hydroxy
groups.
[0090] Examples of the acid sealing agent include carbodiimide
compounds, epoxy compounds, amine compounds, isocyanate compounds,
and alcohols.
[0091] Among these, from the perspective of obtaining an innermost
layer that is superior with regards to deterioration resistance
performance, carbodiimide compounds and epoxy compounds are
preferable.
[0092] Additionally, from the perspective of achieving superior
handling, the acid sealing agent is preferably a solid as room
temperature (23.degree. C.).
[0093] From the perspective achieving sealability of at least the
carboxylic acid included in the polyamide, a preferable form of the
acid sealing agent is one by which the carboxylic acid (including
partial esters) can at least be sealed, etc.
[0094] Note that, in the present invention, the acid sealing agent
that seals, etc. at least the carboxylic acid is referred to as a
"carboxylic acid sealing agent".
[0095] Examples of the carboxylic acid sealing agent include
carbodiimide compounds, epoxy compounds, amine compounds,
isocyanate compounds, and alcohols.
[0096] If the acid sealing agent is the carboxylic acid sealing
agent, the carboxylic acid sealing agent can seal, etc. phosphoric
acid and sulfonic acid, in addition to the carboxylic acid, and
also partial esters thereof.
[0097] The following description of the acid sealing agent applies
to the carboxylic acid sealing agent.
[0098] The carbodiimide compound used as the acid sealing agent is
not particularly limited as long as it is a compound having a
carbodiimide group (--N.dbd.C.dbd.N--). Examples thereof include
polycarbodiimide and monocarbodiimide.
[0099] Of these, from the perspective of obtaining an innermost
layer that is superior with regards to deterioration resistance
performance, polycarbodiimide is preferable.
[0100] The polycarbodiimide that can be used in the present
invention is not particularly limited as long as it has multiple
carbodiimide groups in the molecular chain (e.g. the polymer
backbone). The polycarbodiimide can be obtained by, for example,
condensing an arbitrary organic diisocyanate, and a conventional
technology can be used for the method thereof. For example, a
product obtained via a decarboxylation condensation reaction of the
organic diisocyanate can be used.
[0101] Examples of the polycarbodiimide include urea additives of
poly[1,1-dicyclohexylmethane(4,4-diisocyanate)] and
cyclohexylamine, and the like.
[0102] Preferable forms of commercially available polycarbodiimides
include Carbodilite HMV-8CA and Carbodilite LA-1, manufactured by
Nisshinbo Holdings Inc., polycarbodiimide compounds that are fine
granulates at room temperature, and the like due to their being
readily available and usability.
[0103] The monocarbodiimide that can be used in the present
invention is not particularly limited as long as it has one
carbodiimide group. Specific examples include dimethyl
carbodiimide, diethyl carbodiimide, diisopropyl carbodiimide,
diisobutyl carbodiimide, dioctyl carbodiimide, t-butyl isopropyl
carbodiimide, di-t-butyl carbodiimide, dicyclohexyl carbodiimide,
diphenyl carbodiimide, 2,2,6,6-tetramethyl diphenyl carbodiimide,
2,2,6,6-tetraethyl diphenyl carbodiimide, 2,2,6,6-tetraisopropyl
diphenyl carbodiimide, di-.beta.-naphthyl carbodiimide, and the
like.
[0104] A description of the epoxy compound is given below.
[0105] The epoxy compound used as the acid sealing agent is not
particularly limited as long as it is a compound having at least
one epoxy group.
[0106] Examples of the epoxy compound include polymers containing
the epoxy group such as epoxy group-containing (meth)acrylic
polymers, epoxy group-containing polystyrenes, and epoxidized soy
bean oil; glycidyl esters (including polymers and monomers); and
glycidyl ethers (including polymers and monomers).
[0107] From the perspectives of obtaining an innermost layer that
is superior with regards to deterioration resistance performance
and a composition that is not prone to gelling, an epoxy equivalent
weight of the epoxy compound is preferably from 140 to 3,300
g/eq.
[0108] When the epoxy compound is a polymer containing the epoxy
group, from the perspectives of obtaining an innermost layer that
is superior with regards to deterioration resistance performance
and a composition that is not prone to gelling, the epoxy
equivalent weight thereof is preferably from 170 to 3,300 g/eq.
[0109] When the epoxy compound is a monomer containing the epoxy
group, from the perspectives of obtaining an innermost layer that
is superior with regards to deterioration resistance performance
and a composition that is not prone to gelling, the epoxy
equivalent weight thereof is preferably from 140 to 400 g/eq.
[0110] Of these epoxy compounds, from the perspectives of obtaining
an innermost layer that is superior with regards to deterioration
resistance performance and a composition that is not prone to
gelling, epoxy group-containing (meth)acrylic polymers and glycidyl
ethers (including polymers and monomers) are preferable.
[0111] Additionally, from the perspectives of obtaining an
innermost layer that is superior with regards to deterioration
resistance performance and a composition that is not prone to
gelling, epoxy group-containing (meth)acrylic polymers (especially
those that are solid at room temperature) are preferable.
[0112] A description of the epoxy group-containing (meth)acrylic
polymer is given below.
[0113] The epoxy group-containing (meth)acrylic polymer used as the
acid sealing agent is not particularly limited as long as the
backbone is a (meth)acrylic polymer and is a polymer that has at
least one epoxy group.
[0114] Note that in the present invention, (meth)acrylic means
acrylic and/or methacrylic.
[0115] The (meth)acrylic polymer used as the backbone may be either
a homopolymer or a copolymer.
[0116] An example of the epoxy group-containing (meth)acrylic
polymer is a methyl methacrylate.glycidyl methacrylate
copolymer.
[0117] From the perspectives of obtaining an innermost layer that
is superior with regard to deterioration resistance performance and
a composition that is not prone to gelling and that has superior
handling, a weight average molecular weight of the epoxy
group-containing (meth)acrylic polymer is preferably from 5,000 to
300,000 and more preferably from 8,000 to 250,000.
[0118] Among these, from the perspectives of obtaining an innermost
layer that is superior with regards to deterioration resistance
performance, and a composition that is not prone to gelling and
that has superior handling, the epoxy group-containing
(meth)acrylic polymer is preferably a methyl methacrylate.glycidyl
methacrylate copolymer.
[0119] A description of the glycidyl ether is given below.
[0120] The glycidyl ether used as the acid sealing agent is not
particularly limited as long as it is a compound having a
glycidyloxy group.
[0121] Examples of the glycidyl ether include butyl-glycidyl ether,
2-ethylhexyl glycidyl ether, stearyl-glycidyl ether, allyl-glycidyl
ether, phenyl-glycidyl ether, butylphenyl-glycidyl ether,
butoxy-polyethyleneglycol-glycidyl ether, glycidol,
glycerin.epichlorohydrin-0 to 1 mol additive-polyglycidyl ether,
ethylene glycol-epichlorohydrin-0 to 2 mol additive-polyglycidyl
ether, polyethyleneglycol-diglycidyl ether, neopentyl
glycol-diglycidyl ether, and trimethylolpropane-polyglycidyl
ether.
[0122] A commercially available product can be used as the epoxy
compound.
[0123] Examples of commercially available products that can be used
as the epoxy group-containing (meth)acrylic polymer include
MARPROOF G-0150M (acrylic polymer, powder, weight average molecular
weight: 8,000 to 10,000, epoxy equivalent weight: 310 g/eq,
manufactured by NOF Corporation) and MARPROOF G-2050M (acrylic
polymer, powder, weight average molecular weight: 200,000 to
250,000, epoxy equivalent weight 340 g/eq, manufactured by NOF
Corporation).
[0124] Examples of commercially available products that can be used
as the epoxy group-containing polystyrene include MARPROOF G-1010S
(styrene-based polymer, powder, weight average molecular weight:
100,000, epoxy equivalent weight 1,700 g/eq, manufactured by NOF
Corporation).
[0125] Examples of commercially available products that can be used
as the epoxidized soy bean oil include Newsizer 510R (manufactured
by NOF Corporation).
[0126] A single acid sealing agent can be used or a combination of
two or more acid sealing agents can be used.
[0127] From the perspectives of obtaining an innermost layer that
is superior with regards to deterioration resistance performance
and a composition that is not prone to gelling, an amount of the
acid sealing agent is preferably from 0.1 to 10 parts by mass and
more preferably from 0.5 to 5 parts by mass per 100 parts by mass
of the polyamide.
[0128] From the perspectives of obtaining an innermost layer that
is superior with regards to deterioration resistance performance
and a composition that is not prone to gelling, when the acid
sealing agent is a carbodiimide composition, the amount thereof is
preferably from 0.1 to 2 parts by mass and more preferably from 0.3
to 1 part by mass per 100 parts by mass of the polyamide.
[0129] From the perspectives of obtaining an innermost layer that
is superior with regards to deterioration resistance performance
and a composition that is not prone to gelling, when the acid
sealing agent is an epoxy composition, the amount thereof is
preferably from 0.1 to 10 parts by mass and more preferably from
0.5 to 5 parts by mass per 100 parts by mass of the polyamide.
[0130] From the perspectives of obtaining an innermost layer that
is superior with regards to deterioration resistance performance
and a composition that is not prone to gelling, a total amount of
the acid acceptor and the acid sealing agent is preferably from 3
to 20 parts by mass and more preferably from 5 to 15 parts by mass
per 100 parts by mass of the polyamide.
[0131] From the perspectives of obtaining an innermost layer that
is superior with regards to deterioration resistance performance
and a composition that is not prone to gelling, with regards to a
weight ratio of the acid sealing agent to the acid receptor, the
amount of the acid sealing agent is preferably from 50 to 150 parts
by mass and more preferably from 70 to 130 parts by mass per 100
parts by mass of the acid acceptor.
[0132] The polyamide resin composition can comprise additives as
desired, as long as the object of the present invention is not
hindered. Examples of additives include fillers, reinforcing
agents, antiaging agents, plasticizers, pigments (dyes),
tackifiers, lubricants, dispersing agents, and processing aids.
[0133] A manufacturing method of the polyamide resin composition is
not particularly limited. Examples thereof include a method wherein
the polyamide and the acid acceptor, along with, as required, the
acid sealing agent and/or the additives, are mixed using a twin
screw kneader extruder.
[0134] From the perspective of achieving superior mixing
processability, a mixing temperature is preferably from 180 to
300.degree. C. and more preferably from 200 to 280.degree. C.
[0135] A Young's modulus of a hardened product (e.g. a sheet)
formed from the polyamide resin composition is preferably 300 MPa
or less and more preferably 270 MPa or less.
[0136] Additionally a Young's modulus of a hardened product (e.g. a
sheet) formed from the polyamide resin composition after a test in
which the hardened product is immersed in a refrigerant-containing
composition including water is preferably 300 MPa or less and more
preferably 270 MPa or less. When the Young's modulus of a hardened
product after the immersion test described above is 300 MPa or
less, superior deterioration resistance performance of the
innermost layer, superior flexibility (low flexural rigidity of the
hose itself and good manageability in an engine room), and superior
vibration resistance (vibration from a compressor used to compress
the refrigerant does not easily transfer to a vehicle body side and
effects of vibration and noise experienced in the vehicle are
minimal) are obtained. If the Young's modulus of the hardened
product exceeds 300 MPa, the flexural rigidity of the hose itself
will increase, manageability in an engine room will decline,
vibration from a compressor used to compress the refrigerant will
transfer to a vehicle body side, and problems related to vibration
and noise will easily occur.
[0137] In the present invention, the Young's modulus of the
hardened product after the immersion test can be configured to be
300 MPa or less by setting the amount of the acid acceptor to be
from 0.5 to 20 parts by mass per 100 parts by mass of the
polyamide.
[0138] In the present invention, the Young's modulus is measured in
accordance with Japan Industry Standard (HS) K 7161 as follows. A
sheet is fabricated using the polyamide resin composition at a
temperature of 230.degree. C. A sample is cut from the sheet having
the following dimensions: 5 mm (width).times.80 mm
(length).times.0.15 mm (thickness) and this sample was used as a
sample (sample 1 in the Working Examples). Thereafter, an immersion
test is performed by filling an autoclave with a
refrigerant-containing composition including water (the
refrigerant-containing composition including 50 mass % of
HFO-1234yf (manufactured by Honeywell) as a refrigerant and 50 mass
% of ATMOS GU-10 (manufactured by Nippon Oil Corporation) as a
lubricating oil; wherein 0.1 parts by mass of water per 100 parts
by mass of the refrigerant-containing composition are added
thereto) and immersing the sample 1 obtained via the process
described above therein for 168 hours under the following
conditions: heated to 150.degree. C. and pressurized (calculated
value=7 MPa). Then the Young's modulus of the obtained samples
(sample 1 and sample 2 in the Working Examples) is measured at a
tensile speed of 50 mm/minute.
[0139] A description of the rubber layer is given below.
[0140] In the present invention, the inner tube can have a rubber
layer. If the inner tube has a rubber layer, the rubber layer is
positioned adjacent to the innermost layer.
[0141] A description of the rubber composition used when
manufacturing the rubber layer is given below.
[0142] In the present invention, the rubber comprised in the rubber
composition is not particularly limited. Examples of the rubber
include acrylonitrile-butadiene rubber (NBR), natural rubber (NR),
butadiene rubber (BR), styrene-butadiene copolymer rubber (SBR),
polyisoprene rubber (IR), butyl rubber (IIR), chlorobutyl rubber
(Cl-IIR), bromobutyl rubber (Br-IIR), chloroprene rubber,
ethylene-propylene copolymer rubber, styrene-isoprene copolymer
rubber, styrene-isoprene-butadiene copolymer rubber,
isoprene-butadiene copolymer rubber, and chlorosulfonated
polyethylene.
[0143] From the perspectives of achieving superior fatigue
resistance performance and superior permeation resistance, the
rubber preferably comprises butyl rubber (IIR).
[0144] A single rubber can be used or a combination of two or more
rubbers can be used.
[0145] In the present invention, the rubber composition can
comprise additives as desired, as long as the object of the present
invention is not hindered. Examples of additives include
vulcanizing agents, vulcanization accelerators, fillers,
reinforcing agents, antiaging agents, vulcanization activators,
plasticizers, pigments (dyes), tackifiers, lubricants, dispersing
agents, and processing aids.
[0146] In the present invention, a manufacturing method of the
rubber composition is not particularly limited. Examples thereof
include a method wherein the rubber and optionally usable additives
are mixed (kneaded) using an open roll, a kneader, an extruder, a
universal blender, or a batch kneader.
[0147] A description of the reinforcing layer is given below.
[0148] The hose for refrigerant transport use of the present
invention can maintain retention force and obtain superior pressure
resistance and clamp crimping fixing force by comprising the
reinforcing layer.
[0149] Material for the reinforcing layer that can be comprised in
the hose for refrigerant transport use of the present invention is
not particularly limited.
[0150] Examples of the material used from the reinforcing layer
includes fiber materials such as polyester-based fiber,
polyamide-based fiber, aramid fiber, vinylon fiber, rayon fiber,
poly-p-phenylene-benzobisoxazole (PBO) fiber, polyketone fiber, and
polyarylate fiber; and metal materials such as hard steel wire
(e.g. brass-plated wire, zinc-plated wire, and the like), and the
like.
[0151] Among these, from the perspectives of obtaining a
reinforcing layer having superior fatigue resistance and achieving
superior cost performance relative to predetermined desired
performance factors, polyester-based fiber is preferable.
[0152] A shape of the reinforcing layer is not particularly
limited. Examples thereof include braid wind shape and spiral wind
shape.
[0153] A single reinforcing layer can be used or a combination of
two or more reinforcing layers can be used.
[0154] A description of the outer layer is given below.
[0155] In the hose for refrigerant transport use of the present
invention, the reinforcing layer can be protected and superior
external moisture invasion resistance can be achieved by comprising
the outer layer.
[0156] An example of a preferable form of the outer layer that can
be comprised in the hose for refrigerant transport use of the
present invention is a rubber layer.
[0157] Material for the outer layer that can be comprised in the
hose for refrigerant transport use of the present invention is not
particularly limited. Examples of the material used for the outer
layer include other rubber compositions in addition to the same
material used in the rubber layer of the present invention.
[0158] From the perspective of achieving superior weatherability,
ethylene-propylene copolymer rubber is preferably comprised, and
from the perspective of achieving superior permeation resistance,
butyl rubber (IIR) is preferably comprised.
[0159] A method of manufacturing the hose for refrigerant transport
use of the present invention is not particularly limited. Examples
thereof include subsequently laminating the innermost layer, the
rubber layer, the reinforcing layer, and the outer layer on a
mandrel and, thereafter, bonding these layers via vulcanizing.
Additionally, a bonding treatment between the innermost layer and
the rubber layer (e.g. application of an adhesive or surface
treatment of the innermost layer) can be performed. A bonding
treatment between the rubber layer and the reinforcing layer (e.g.
application of an adhesive) can be performed. When the outer layer
is a rubber layer that is the same as the rubber layer of the inner
tube, a bonding treatment between the reinforcing layer and the
outer layer (e.g. application of an adhesive) can be performed.
[0160] From the perspective of achieving superior processability,
in the present invention, a temperature of the polyamide resin
composition when the innermost layer is discharged is preferably
from 230 to 250.degree. C.
[0161] From the perspective of achieving superior rubber quality
and economical efficiency, a temperature when vulcanizing is
preferably from 130 to 180.degree. C.
[0162] From the perspective of achieving superior rubber quality
and economical efficiency, a vulcanizing time is preferably from 30
to 120 minutes.
[0163] Examples of vulcanization methods include press
vulcanization, steam vulcanization, oven vulcanization (dry heat
vulcanization), and hot water vulcanization.
[0164] The refrigerant-containing composition that can be used in
the hose for refrigerant transport use of the present invention is
not particularly limited. Examples thereof include compositions
comprising a refrigerant such as fluorine-based compounds and a
lubricant.
[0165] Examples of the refrigerant comprised in the
refrigerant-containing composition include fluorine-based compounds
having double bonds; and saturated hydrofluorocarbons such as
HFC-134a (structural formula: CF.sub.3--CFH.sub.2).
[0166] Examples of the fluorine-based compounds having double bonds
include fluoropropenes such as 1,2,3,3,3-pentafluoropropene,
1,3,3,3-tetrafluoropropene, 2,3,3,3-tetrafluoropropene (structural
formula: CF.sub.3--CF.dbd.CH.sub.2, HFO-1234yf),
1,2,3,3-tetrafluoropropene, and 3,3,3-trifluoropropene.
[0167] The innermost layer comprised in the hose for refrigerant
transport use of the present invention has superior deterioration
resistance performance with respect to fluorine-based compounds
having double bonds such as fluoropropenes (particularly, new
refrigerants such as HFO-1234yf). Additionally, by enhancing the
deterioration resistance performance of the innermost layer, the
innermost layer becomes resistant to cracking due to deformation
and/or vibrating of the hose for refrigerant transport use, which
leads to an improvement in the dynamic fatigue properties of the
innermost layer.
[0168] The lubricating oil comprised in the refrigerant-containing
composition is not particularly limited. Examples thereof include
conventionally known products.
[0169] The hose for refrigerant transport use of the present
invention can be used to transport a refrigerant, and, for example,
can be used as a hose for transporting fluids such as a hose for
use in air conditioning systems (e.g. car air conditioning
systems). Additionally, the hose for refrigerant transport use of
the present invention can be used, for example, as a hose for
transporting hot water (temperature regulator use) in addition to
being usable as a hose for use in air conditioning systems.
Working Examples
[0170] The present invention is described below in detail using
working examples but the present invention is not limited to such
working examples.
Evaluation
[0171] Samples obtained according to the process described below
were subjected to immersion testing and tensile test via the
following methods. The tensile strength (T.sub.B), elongation
(E.sub.B), and condition of the sample after immersion testing were
evaluated. The results are shown in the table in FIGS. 2a-2b.
1. Fabrication of Sample 1
[0172] A sheet was fabricated from a polyamide resin composition
obtained via the process described below using an electric heating
press at a temperature of 230.degree. C. A sample was cut from the
sheet having the following dimensions: 5 mm (width).times.80 mm
(length).times.0.15 mm (thickness) and this sample was used as
sample 1.
2. Immersion Test (Accelerated Deterioration Test)
[0173] The immersion test was performed by filling an autoclave
with a refrigerant-containing composition including water (the
refrigerant-containing composition including 50 mass % of
HFO-1234yf (manufactured by Honeywell) as a refrigerant and 50 mass
% of ATMOS GU-10 (manufactured by Nippon Oil Corporation) as a
lubricating oil; wherein 0.1 parts by mass of water per 100 parts
by mass of the refrigerant-containing composition are added
thereto) and immersing the sample 1 obtained according to the
process described above therein for 168 hours under the following
conditions: heated to 150.degree. C. and pressurized (calculated
value=7 MPa).
[0174] Following the immersion test, the sample 1 was removed from
the refrigerant-containing composition including water. The
post-immersion test sample is referred to as sample 2.
3. Tensile Test
[0175] The tensile strength (T.sub.B) and elongation (E.sub.B) at
23.degree. C. of the sample 1 and sample 2 that were obtained via
the processes described above were measured in accordance with
Japan Industry Standard (JIS) K 7161. Tensile speed was set at 50
mm/minute.
4. Evaluation of the Conditions of the Sample Before and after the
Immersion Test
[0176] The sample 1 and sample 2 that were obtained via the
processes described above were bent and the conditions of the
sample before and after the immersion test were evaluated.
5. Young's Modulus (Tensile Modulus of Elasticity)
[0177] The Young's modulus of the sample 2 that was obtained via
the processes described above was measured in accordance with JIS K
7161 at a tensile speed of 50 mm/minute.
Manufacture of the Polyamide Resin Composition
[0178] The polyamide resin composition was manufactured by
uniformly mixing the components shown in the table in FIGS. 2a-2b
at the amounts (parts by mass) also shown in the table using a twin
screw kneader extruder.
[0179] The components shown in the table are as follows. [0180]
Polyamide (1): A blend of polyamide 6 and a carboxyl
group-containing modified polyolefin (Zytel ST811HS, manufactured
by DuPont) [0181] Polyamide (2): Polyamide 11 (RILSAN BESNO TL,
manufactured by Arkema Inc.) [0182] Acid acceptor 1: Calcium
hydroxide (lime hydrate), manufactured by Irimajiri Sekkai
Industry, Co., Ltd. [0183] Acid acceptor 2: Magnesium oxide (Kyowa
Mag 150, manufactured by Kyowa Chemical Industrial Co., Ltd.)
[0184] Acid acceptor 3: Hydrotalcite (KW-2200, manufactured by
Kyowa Chemical Industrial Co., Ltd.) [0185] Acid acceptor 4:
Hydrotalcite (DHT-4A-2, manufactured by Kyowa Chemical Industrial
Co., Ltd.) [0186] Acid sealing agent 1: Methyl
methacrylate.glycidyl methacrylate copolymer (MARPROOF G-2050M,
weight average molecular weight: 200,000 to 250,000; epoxy
equivalent weight: 340 g/eq; manufactured by NOF Corporation)
[0187] It is clear from the results shown in the table in FIGS.
2a-2b that the sample of Comparative Example 1, which did not
comprise an acid acceptor, was brittle after the immersion test and
had an innermost layer with inferior deterioration resistance
performance. The sample of Comparative Example 2 wherein the amount
of the acid acceptor was less than 0.5 parts by mass per 100 parts
by mass of the polyamide cracked when bent after the immersion test
and had an innermost layer with inferior deterioration resistance
performance. With the sample of Comparative Example 3 wherein the
amount of the acid acceptor exceeded 20 parts by mass per 100 parts
by mass of the polyamide, the hardness of the cured product of the
polyamide resin composition after the immersion test was excessive
and the deterioration resistance performance of the innermost layer
was inferior.
[0188] In contrast, with the samples of Working Examples 1 to 11,
declines in the tensile strength (T.sub.B) and elongation (E.sub.B)
of the samples were suppressed, no cracking occurred when bending
after the immersion tests, and innermost layers of hoses for
refrigerant transport use having superior deterioration resistance
performance were obtained. Note that the suppression of the
declines in the tensile strength (T.sub.B) and elongation (E.sub.B)
of the samples and lack of cracking when bending after the
immersion tests are indicators that the samples (innermost layers)
of Working Examples 1 to 11 achieved superior deterioration
resistance performance.
[0189] Additionally, with the samples of Working Examples 1 to 11,
superior flexibility (flexibility of the innermost layer and of the
entire hose) was achieved due to the post-immersion test Young's
modulus being within a suitable range and the samples not becoming
excessively hard.
[0190] Additionally, with the sample of Working Example 8 that
comprised an acid acceptor (hydrotalcite) with a lower OH content
than that of Working Example 10, the declines in the tensile
strength (T.sub.B) and elongation (E.sub.B) of the sample were
further suppressed. Thus, it is clear that using a hydrotalcite
having a lower OH content or Mg.sub.1-xAl.sub.xO.sub.3.83x as the
acid acceptor leads to obtaining an innermost layer that is
superior with regards to deterioration resistance performance.
Working Example 12
Manufacture of Hose 1
[0191] A hose was manufactured by extruding an innermost layer
having a thickness of 0.15 mm using the polyamide resin composition
of Working Example 1 with a resin extruder on a surface of a
mandrel made from thermoplastic resin having an outer diameter of
11 mm (extrusion temperature: 240.degree. C.). A tube rubber layer
(hereinafter "butyl rubber composition A") having a thickness of
1.2 mm was extruded on a surface of the innermost layer, and a
two-layer reinforcing layer made by alternately winding
polyethylene terephthalate (PET) fiber having a gross thread
thickness of 80,000 dtex in a spiral wind shape was formed. A cover
rubber layer (having the same composition as the butyl rubber
composition A) having a thickness of 1.0 mm was extruded on a
surface of the reinforcing layer and formed into an extruded outer
layer. Furthermore, a conventional polymethylpentene resin was
extruded on the extruded outer layer and formed into a cover skin.
The obtained tube shaped laminate was vulcanized for 100 minutes at
160.degree. C. and, thereafter, the cover skin and the mandrel were
removed from the tube shaped laminate.
[0192] The hose for refrigerant transport use of Working Example 12
comprises the innermost layer of Working Example 1, which, as
described above, has superior deterioration resistance
performance.
[0193] Butyl rubber composition A (same composition for tube rubber
and cover rubber): Composition consisting of 100 parts by mass of
butyl rubber, 80 parts by mass of carbon black (HAF), 3 parts by
mass of stearic acid, 10 parts by mass of paraffin oil, 2 parts by
mass of zinc oxide, and 8 parts by mass of brominated alkyl phenol
formaldehyde resin.
Working Example 13
Manufacture of Hose 2
[0194] A hose 2 was manufactured in the same manner as the hose 1
of Working Example 12, with the exception that the polyamide resin
composition of Working Example 1 was replaced by the polyamide
resin composition of Working Example 7.
[0195] The hose for refrigerant transport use of Working Example 13
comprises the innermost layer of Working Example 1, which, as
described above, has superior deterioration resistance
performance.
* * * * *